Comparison of VACUETTE® Serum Gel tubes with
Therapeutic Drug Monitoring (TDM) in Serum
Background:
Greiner-Bio-One, Austria has sold plastic evacuated
tubes (VACUETTE®) for venous blood collection
VACUETTE® Gel Tubes incorporate an inert gel
material into the blood collection tube. These gels have a controlled viscosity and a specific gravity
intermediate to serum and clot. During centrifugation,
the gel material forms an impermeable barrier
The samples were analyzed for 15 TDM parameters
on the following instruments according to
Gel Z has been in development since 2001 and has
manufacturer's instructions and protocols and using
the same components as the last gel type (Gel P3),
the difference being the production process, which
Tested DrugAnalyzer
has been optimised. The gel might be slightly more
yellow in colour however provides the better
performance than the last gel type as well as
providing the advantage of a more stable barrier,
which is particularly beneficial during transport.
Preanalytical handling remains the same and does
not require any changes (i.e. centrifugation
Study Objective:
The aim was to study the stability of a variety of
commonly monitored drugs in serum after storage in
VACUETTE® serum separator tubes on Gel Z or Gel P3N in comparison to a plain glass VACUTAINER®
Study design:
Three tube types were evaluated in this study:
Results – Evaluation:
There are two graphs shown for each drug tested, for
one displaying low and the other displaying high drug quality control level (pink: VACUETTE® Gel Z, yellow:
A serum pool was prepared by combining residual
VACUETTE® Gel P3N, blue: Vacutainer® plain glass
samples. This serum pool was split into two for each
drug tested and each half was spiked with commercial quality control material (BioRad Muliqual
Level III) to create a "low" and a "high" level to reflect
Results / Comments:
the lower and the upper end of the therapeutic range.
Percent recovery was calculated and was expected
For each tube to be evaluated, two sets of duplicate
to fall within +/-10% of the initial time control tube
tubes were labelled 0, 4, 24, and 48 h. 3,0 ml of "low"
values. Values falling below 90% or above 110%
pool was aliquoted into one set of duplicate tubes
recovery were considered clinically significant.
and 3,0 ml "high" pool was aliquoted into the second
Stability of the drug on the gel up to 48 hours was
shown for all of the 15 drugs tested. These included
Immediately after aliquoting, the samples were
the analgesics Acetaminophen, Carbamazepine, and
analyzed in duplicate to obtain the "0 hours" values.
Salicylate; the antibiotics Gentamycin, Tobramycin,
The tubes were then stored at 4°C and the serum
and Vancomycin; the anti-epileptics Phenobarbital,
was analyzed in duplicate at 4, 24, and 48 h.
Phenytoin, and Valproic Acid; the anti-arrhythmic drug Procainamide and its metabolite n-Acetylprocainamide; the cardiac glycoside Digoxin; the alcohol ethanol; tricyclic antidepressants and the anti-spasmodic Theophylline.
Conclusion:
From these findings we conclude, that tubes
The stability of therapeutic drugs in serum stored in
containing Gel Z performed comparably to tubes
gel tubes has been widely investigated. The
containing Gel P3N and plain glass tubes, and that
absorption of drugs into the gel is dependent upon
several factors including the chemical nature of the
References:
gel and of the drug itself, time on the gel, temperature
(1) Dasgupta A., Yared M.A., Wells A., Time-
dependent absorption of therapeutic drugs by
In this current study the stability of 15 drugs added to
the gel of the Greiner Vacuette® blood collection
a serum pool under laboratory conditions was
examined. Tubes containing Gel Z showed constant
(2) Mutschler Ernst, Arzneimittelwirkungen.
drug level over 48 hours for most of the analytes
Wissenschaftliche Verlagsgesellschaft mbH
tested and no clinical significance was observed.
Annex / Results – Raw Data: Recovery after x hours [%] Concentration Tube Type Recovery after x hours [%] Concentration Tube Type Acetaminophen lowAcetaminophen highCarbamazepine lowCarbamazepine highDigoxin lowDigoxin highEthanol lowEthanol highGentamycin lowGentamycin highn-Acetylprocainamide lown-Acetylprocainamide highPhenobarbital lowPhenobarbital highPhenytoin lowPhenytoin highProcainamide lowProcainamide highSalicylate lowSalicylate highTheophylline lowTheophylline highTobramycin lowTobramycin highTricyclic Antidepressants lowTricyclic Antidepressants highValproic Acid lowValproic Acid highVancomycin lowVancomycin high

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